The present invention relates to microfluidic devices, and more particularly, to a method and apparatus for distributing fluid on a microfluidic device.
Methods of making a homologous series of compounds, or the testing of new potential drug compounds comprising a series of light compounds, has been a slow process because each member of a series or each potential drug must be made individually and tested individually. For example, a plurality of potential drug compounds is tested by an agent to test a plurality of materials that differ perhaps only by a single amino acid or nucleotide base, or a different sequence of amino acids or nucleotides.
The processes described above have been improved by microfluidic chips which are able to separate materials in a and move the materials through the microchannel is possible. Moving the materials through microchannels is possible by use of various electro-kinetic processes such as electrophoresis or electro-osmosis. Fluids may be propelled through various small channels by the electro-osmotic forces. An electro-osmotic force is built up in the channel via surface charge buildup by means of an external voltage that can repel fluid and cause flow.
Another method for the movement of fluids is the use of an electrohydrodynamic pump. In electro-osmotic and electrohydrodyamic pumping, electrodes are placed within the microfluidic structure.
In fluid delivery in microfluidic structures, it is important to distribute approximately the same fluid volume to each reaction well. In using certain fluids, however, even distribution within reaction wells is difficult to accomplish.
It is, therefore, one object of the invention to provide an improved fluid delivery mechanism to an array of reaction wells. It is a further object of the invention to provide a reliable method for delivering fluid to reaction wells.
It is another object of the present invention to create a relatively small device which can carry out hundreds and even thousands of chemical experiments simultaneously, create new compounds, and measure their reactivities.
It is yet another object of the present invention to provide a liquid handling drug discovery and diagnostic tool which increases the speed and productivity of discovering new drug candidates and does so on a miniaturized scale or platform that reduces cost and manual handling. It is still a further object of the present invention to provide a multiple fluid sample processor, system and method which is capable of conveying, transporting, and/or processing samples in a large multiplicity of sites without exposure to the atmosphere.
In one aspect of the invention, a microfluidic fluid delivery system includes a microfluidic chip having a fluid input. A fluid reservoir is coupled to the fluid input. A gas delivery system has a gas pressure source and a variable amplitude function generator generating an alternating signal. A valve is coupled to the function generator and the gas pressure source. The valve controls the gas pressure in response to said alternating signal. The gas pressure displaces fluid from the fluid reservoir into the fluid input.
In a further aspect of the invention, a method of distributing fluid to a microfluidic chip comprises the steps of: providing a reservoir having fluid therein; generating an alternating pressure to cyclically pressurize fluid within a microfluidic device; filling capillary channels in the microfluidic device until each channel is filled to a capillary break; increasing the amplitude of the alternating pressure; and thereby, overcoming the capillary break in response to the increase in the amplitude.
One advantage of the invention is that small and controlled amounts of fluid may be delivered in an array structure with microchannels that have high pressure losses. Another advantage of the invention is that the method for delivering fluid to microfluidic structures is applicable to structures having high integration densities and where viscous losses in microchannels are significant.
Other objects and features of the present invention will become apparent when viewed in light of the detailed description of the preferred embodiment when taken in conjunction with the attached drawings and appended claims.